A microphone is attached to the main unit. Cartridges use a proprietary form factor.Fukutate Publishing StudyBox

Incorporates a cassette player into the main unit, used for educational purposes with a wide variety of cassettes. The closest thing I can think of to this is the KidVid Controller for the Atari 2600.

Realtec Game Genie

The Game Genie was released for the Famicom with a 60-pin connector, licensed by Codemasters. Unlike the NES version it does not have a handle.

Prevo FC Pro Action Replay

A cheat device that works like the Game Genie, this was released in 2003, the year the Famicom manufacturing would be discontinued. Being a much more recent device than the Game Genie, it comes with built-in codes for at least 124 games. Devices that Plug into the Famicom Expansion Port

Requires Family BASIC Keyboard or certain 3rd Party Joysticks like the ASCII Stick II Turbo. Also the Hori S.D. Station has the jacks for saving and recording, an expansion port passthrough and headphones.

This is a potentiometer with a button. Unlike the NES controller, there is no externally accessible trimmer for the potentiometer on the Famicom controllers. The Arkanoid II controller (blue/green color scheme) has a port for a second paddle controller for the second player. It can also be used with the Keyboard and Data Recorder for saving levels. The original Arkanoid (black/red color scheme) controller does not. Neither Japanese controller has a trimmer capacitor, so they will typically not get all the way to the right side of the screen.

IGS Battle Box
Armadillo
Battle Stadium: Senbatsu Pro Yakuu

Optional for both cartridges

This is a save accessory for the above games like the ASCII Turbo File. Armadillo does not have battery backed RAM, Battle Stadium does. It appears to use 512 bytes of EEPROM for saving.

Optional for all games, this is a controller with a trackball instead of a D-pad.

Konami Hyper Shot
Hyper Olympic
Hyper Olympic Gentaiban!
Hyper Sports

This is a pair of boxes with only two large buttons ("run" and "jump" on each box to facilitate gameplay in these games. Two players supported. Also released for the MSX & SG-1000. A similar device was released for the Atari 2600 as the Track & Field controller.

Capcom Mahjong Keypads
Ide Yosuke Jissen Mahjong (included)

Ide Yosuke Jissen Mahjong II (included)

Capcom released a keypad with each of these mahjong games, and I have read that they are not interchangeable despite having the same buttons.

The Turbo File is a detachable device you can use to save games and data. Many of these games already had internal battery backed RAM for saving, but this device allowed you extra storage. Both Turbo File devices have a battery backed RAM saving. The original Turbo File came with only 8KB, usually enough for one game. The Turbo File II came with 32KB, selectable in four slots of 8KB.

Famicom Modem Keypad

Nintendo Family Computer Network System (included)

Power Glove
No games released in Japan

NES Equivalent : Power Glove (incompatible)

Other PeripheralsFamily Computer Robot
Robot Gyro
Robot Block

NES Equivalent : R.O.B.

Nichibutsu Crazy Climber Sticks
Crazy Climber (included)

These sticks fit on top of the D-pads of both Famicom controllers. You hold the controllers perpendicular to the screen. A pair of NES Advantage joysticks would work just as well.

NES Peripheral List

Devices that Plug into the Cartridge Slot

Game Genie

A plug in device from Codemasters that allows the player to input three cheat codes which change values in the ROM. Has a very rare adapter, originally sold separately, to fit inside the NES Top Loader. Distributed by Camerica in Canada, Galoob in the U.S. It was also distributed in Europe.Pro Action Replay

A UK cheat device by Datel that looks and functions like a Game Genie, but has a built-in trainer to help players discover new codes and modifies RAM values instead of ROM values.

Game Action Replay

Manufactured by STD Entertainment, this cheat cartridge allows you to save and restore your game at any point, essentially a save state. It has five save slots, but only allows you to save states for one game at a time. It requires you to remove the metal bar in the cartridge cradle inside your front loader.

Aladdin Deck Enhancer

A cartridge housing by Codemasters that accepts compact cartridges. All but one game was available as a normal cartridge.

The Power Pad was originally released as the Family Fun Fitness Mat by Bandai, but Nintendo licensed the concept from Bandai and quickly rebranded it as the Power Pad. The Power Pad has two sides, Side A has six blue lands surrounding two red lands, and Side B has six numbered blue lands on the left and six numbered red lands on the right. In Europe the device retained its original Family Fun Fitness Mat branding and was released by Bandai, but Bandai only released Athletic World and Stadium Events.

The Mattel Power Glove was a positional controller that translated hand and finger movements into controller movements and button presses. It also had a keypad on the side to program commands. Only the above two games have any support for the device outside its abilities to emulate a NES Controller. Both games were unreleased in Europe and Japan.U-Force
U-Force Power Games (prototype)

The U-Force was a 3-D positional controller that used infrared sensors to detect hand movements and convert them into controller movement. While the U-Force tried to emulate a NES Controller, it also had a native mode. Only the prototype game used it.

Miracle Piano Keyboard
Miracle Piano Keyboard Teaching System
The Software Toolworks Miracle Piano was a teaching keyboard with 49 keys. Cartridges using the system were also released for the Genesis and SNES. The Piano is a MIDI piano and can be used with any kind of Miracle Piano software with the right adapter cable. It generates its own audio through the keyboard's built-in speakers, the NES audio is used for a metronome.

Konami LaserScopeLaser Invasion (optional)

The LaserScope was a headset that included speakers to amplify your NES's audio, a targeting reticule for aiming a light gun by sight, a microphone into which you would say "Fire" to shoot and a rapid fire control for the shooting. Essentially it is a head mounted, voice activated and rapid fire capable Zapper. It is compatible with every Zapper game. The intent of the device was to allow you to keep your hands on a controller while firing with the head mounted sight. In Laser Invasion, you can use this device in the Top Gun like helicopter stages and the Operation Wolf like shooting stages, whereas you can only use the Zapper in the latter. Unreleased in Europe.

VAUS ControllerArkanoid
Unlike the Japanese versions of this controller from Taito, this one has a trimmer screw externally accessible to adjust the range of the potentiometer. Unfortunately the awesome Arkanoid II was never released in the US.

Racermate Challenge II Bicycle Trainer
Racermate Challenge II

The Racermate Challenge II kit came with a cartridge and a tracking peripheral set to be connected to an exercise bike. This set came with a bike trainer, an interface box to plug into the controller ports, and a handlebar display. The trainer had to be mounted onto an exercise bike, which would send the rotational data to the interface box and display and the program would react accordingly. Racermate was the only unlicensed controller port peripheral released for the NES. A PAL version of the cartridge does exist.

A company called Exertainment made a similar, but licensed peripheral, for the SNES. But Exertainment sold a bike and a TV monitor stand along with their kit.

Devices that Plug into the Expansion PortENIO Board

The ENIO Board was released in 2012 and allows hardware enthusiasts much more convenient access to the Expansion Port. It also provides the resistors necessary to mix in expansion audio into NES internal audio. Finally, it has IDC headers for a Famicom Expansion Port Cable Adapter, the remaining signals and power.

NES Disk System (Protoype at best)

The expansion port was designed with the Famicom Disk System in mind, If Nintendo had ever released this device, the disk drive would have sat underneath the NES Control Deck and plugged into the Expansion Port. The RAM Adapter would be inserted into the cartridge slot and would communicate with the disk drive via the EXP pins on the cartridge connector.

Minnesota State Lottery System (Prototype)

This was the NES version of the Famicom Modem. It fit underneath the Control Deck and had a cartridge to access the state lottery. Due to the distasteful idea of using a children's "toy" for gambling and the probability that children would use it to gamble, the idea never made it into Minnesota homes. Nintendo's desire to use the device for stock trading and multiplayer gaming also withered away.

Baton Teleplay Modem (Prototype)

This modem was developed principally for online gameplay, and would have communicated at 2,400 baud, and allowed for cross-platform compatibility between the NES, the SNES and the Genesis. The company was not able to acquire licensing and investors pulled out, so it was never released. The XBand modem for the SNES and Genesis was later released by another company, but did not have much success.

Well, I guess this Game Genie is rather for Famiclones than then the Famicom, but still...

"A 60-pin Famicom version of the Game Genie was released under license by Realtec, and was sold in Poland, South America and Taiwan, and likely other countries where 60-pin Famicom clones were common. The box art was largely unmodified from the NES version and still depicted the 72-pin Game Genie."

From: http://bootleggames.wikia.com/wiki/Game_Genie

Also check this out, they even did not change the NES box. :P http://www.famicomworld.com/forum/index.php?topic=4744.0

What about the Famicom gun holster? You need it to play Wild Gunner the "proper" way, watch this commercial: https://youtube.com/watch?v=BDfBqWGbqGg Keeping your gun aimed at the enemy all the time is clearly cheating. :P

BTW, I have heard a rumour that Dendy Famiclone lightguns are more accurate than Zappers. Do we have a way to verify this? Actually, you could write an article about Famiclones, at least about these older Micro Geniuses (known as Dendy in Russia and as Pegasus in Poland) which are belived to replicate the Famicom pretty well.

Maybe this video about popular Famiclones will inspire you in some way (English subtitles available):